1. Field of the Invention
The present invention relates to a tri-state latching radio frequency (RF) switch and, more particularly, to an RF micro electromechanical system (MEMS) switch that is latched in one of three states (tri-states).
2. Description of the Related Art
Radio frequency (RF) micro electromechanical system (MEMS) devices can be used in communications, radar, and WLAN technology. RF MEMS devices include micromachined capacitors, inductors, RF switches, phase shifters, tunable oscillators, etc. These devices have better characteristics than the devices manufactured by the prior art. For example, in comparison to a conventional FET or GaAs PIN diode swithches, RF MEMS switches have characteristics such as low insertion loss, good signal separation, high linearity, and low intermodulation. In particular, RF MEMS switches display good characteristics in a high RF range, for example, in an RF range of more than several GHz.
To reduce the costs of manufacturing RF MEMS devices, complementary metal oxide semiconductor (CMOS) manufacturing and packaging technology can be used. This allows for a CMOS circuit and an RF MEMS device to be easily integrated on a single chip. Most RF MEMS switches use surface micromachining and bulk micromachining at a low temperature.
However, conventional RF switches only have one or two output signals for each input signal. In addition, if an input voltage is removed, the RF switches return to their original states and the signal lines are disconnected.
In order to implement a configuration where there are three output signals for each input signal using conventional RF switches, two dual-output signal RF switches must be connected. However, this configuration increases the complexity of the device.
Accordingly, a new RF switch that has three output signals for each input signal is required.
In addition, an RF switch having a latching system in which an output signal is maintained is required so that the output signal is stable even when the input voltage is removed.